servant's entrance vs service door

servant's entrance and service door both are nouns.

Word	Noun	Adjective	Verb	Adverb
servant's entrance	Yes	No	No	No
service door	Yes	No	No	No

As nouns, servant's entrance and service door are synonyms defined as:

servant's entrance and service door: an entrance intended for the use of servants or for delivery of goods and removal of refuse

Other synonyms of servant's entrance include service entrance.

servant's entrance (noun)	service door (noun)
an entrance intended for the use of servants or for delivery of goods and removal of refuse	an entrance intended for the use of servants or for delivery of goods and removal of refuse